Method for a radio-based distance measurement, frequency synchronization, time synchronization, and a detection and / or prevention of relay attacks with a selection of the radio signals to be used

Abstract

The invention relates to a method for a radio-based distance measurement and additionally a method for detecting and / or preventing relay attacks. The invention also relates to a method for a time and / or frequency synchronization. The aim of the invention is to provide a method with which no coherence information is necessary, in particular neither a phase-coherent switching nor a switching is necessary such that the phase after the switching process is known relative to the phase position prior to the switching process, nor must the change of the phase be determined locally, i.e. in particular in the transmitter prior to the transmission and / or in the receiver with respect to the PLL of the receiver, nor must the change be corrected in the calculation. This is achieved by a time synchronization or a corresponding correction.

Description

[0001] Methods for radio-based distance measurement, frequency synchronization, time synchronization and for detecting and / or preventing relay attacks by selecting the radio signals to be used

[0002] The invention relates to a method for radio-based distance measurement, frequency synchronization, time synchronization and furthermore also to a method for detecting and / or preventing relay attacks.

[0003] It is known to determine the distance between two objects from the exchange of radio signals and to perform frequency synchronization or time synchronization.

[0004] It is also known to synchronize timers in two objects, both via wired and wireless connections. For example, the NTP protocol exists. Synchronization is also provided within the framework of a Bluetooth connection, in which each object has a free-running 28-bit clock with a frequency of 3.2 kHz, and each object determines its offset to a central clock and regularly corrects it. Here, synchronization with an accuracy of approximately 1 25 ns is achieved. Improved time synchronization is also known, for example, from DE1 1 2014004426T5 or "Synchronization in Wireless Sensor Networks Using Bluetooth", Casas et al., Third International Workshop on Intelligent Solutions in Embedded Systems, 2005., ISBN: 3-902463-03-1 .This can be used, for example, to save energy by having one object only receive during specific time slots known to the other object, so that it can transmit at the corresponding times. Clock synchronization is still possible, at least in the event of relatively strong one-sided interference on the radio channel, although such interference makes distance measurement impossible, very inaccurate, or very time-consuming. Synchronization to a clock pulse of a received signal at the signal receiver must be clearly distinguished from the accuracy of time synchronization. Here, two clocks on two objects are not synchronized; rather, the receiving object is set so that it is synchronized with the incoming signal. The signal propagation time is not important, since it does not matter when the signal was sent and / or how long it took to transmit.

[0005] Also known from WO 2022 / 096 091 A1 is a method for determining the distance between two objects. The two objects are time-synchronized to within 10 ns or better, and a first and / or second of the two objects emits signals at multiple frequencies, and the distance between the first and second objects is determined. The method includes deciding whether / which signals from the first or second object are used, in particular based on at least one estimate or determination of the effects of interference on reception at both objects. However, coherence information is required for this.

[0006] In addition, WO 2022 / 096 514 A1 discloses a method for detecting a relay attack, wherein radio signals with different frequencies are transmitted between a first and a second object and phase measurements and propagation time measurements are carried out on these radio signals and the change in the phase measurements when the frequency changes is compared with the signal propagation measurements or their change and wherein a relay attack is assumed if a deviation of a predetermined value or a deviation determined from measurements on the radio signals is exceeded.

[0007] For distance determination, it is known to work with in-line phase return, i.e. to use the measured phase of a received signal and to modify the phase of the response signal sent in response based on the measured phase. This is done by adding the measured phase to a predetermined phase position and sending the response signal with the phase position obtained by this addition. From US 8,446,254 B2, for example, it is known to send back the response signal with exactly the phase of the received interrogation signal, but this still has the disadvantage that temporal information is missing. This can also be seen as a corresponding in-line phase return, in which, for example, the received phase of the interrogation signal is always added to the phase zero for the transmission of the response signal. If the predetermined phase were not zero here, but that of a PLL whose phase position relative to the common time is known, this would bring further advantages.

[0008] The object of the invention is to provide a method in which no coherence information is necessary, in particular neither a phase-coherent switching nor a switching such that the phase after the switching is known relative to the phase position before the switching, is necessary and also the change in the phase is not determined locally, in particular at the transmitter before the transmission and / or at the receiver with respect to the PLL of the receiver, and this change must be corrected in the calculation.

[0009] The problem is solved by temporal synchronization or a corresponding correction.

[0010] According to the invention, for determining the distance by means of radio signals or detecting relay attacks, in particular for determining the distance by means of radio signals, between two objects, each having a timer, wherein the two objects emit radio signals on several frequencies and the radio signals are received by the non-transmitting of the two objects, and the receiving object carries out at least one measurement of the phase and / or at least one measurement of the signal arrival time and / or the signal propagation time relative to its timer for each frequency and / or radio signal and responds thereto by emitting at least one radio signal, in particular at approximately the same or the same frequency,wherein the non-responding object of the two objects receives the at least one radio signal emitted in response and carries out at least one measurement of the phase and / or at least one measurement of the signal arrival time and / or signal propagation time relative to its clock for each frequency and / or radio signal, and from this, and in particular the knowledge of the times of emission of features of the signals relative to the clock of the emitting object and / or based on an in-line phase return, in which in particular the received phase is added to the phase otherwise intended for emission, at least one determination of the phase shift, in particular caused by the transmission, and / or at least one determination of the signal propagation time per frequency is carried out, and on the basis of the at least one determination, an evaluation is carried out which in particular determines and / or ascertains the distance between the first and second object,whether a relay attack is present and / or makes a release decision, a determination of a time deviation between the timers of the objects, and in particular also of at least a relative drift of the timers of the objects, is carried out, and the method includes, at least for each frequency and / or each signal round-trip time period, a decision as to whether the measurements on the at least one signal of the first and / or second object are used for the distance determination and / or the detection, wherein the decision is made in particular on the basis of at least one estimation or determination of the effects of interference on reception at both objects, in particular their ratio and / or difference, in particular on the basis of amplitudes, channel and / or measurement quality indicators, such as the number and / or frequency of bit errors, signal reception amplitude differences and / or CQI,whereby for the distance determination and / or detection the selected measurements are corrected for the influence of the determined time deviation and the determined drift.,

[0011] The measurement of the phase shift is understood in particular to mean the signal propagation of the signal round trip between objects one and two.

[0012] Advantageously, the method is carried out in such a way that, in order to determine the time deviation and / or drift, the relative phase position of two radio signals of different frequencies is known by means of the PLL of an object as a function of the time difference of the generation or emission of the two signals at one of the objects relative to its timer, in particular by measurement or corresponding generation, and / or the phase position of the PLL of each of the objects at different frequencies is known relative to its timer, in particular by measurement or corresponding generation, wherein the determination of the time deviation and / or drift between the objects is carried out radio-based by means of phase measurement(s) on a plurality of the radio signals of different frequencies transmitted between the two objects.

[0013] The time deviation and / or drift is advantageously determined by determining the phase shift of the transmission of the forward signal from the first to the second object and the return signal from the second to the first object using in-line phase return. This provides a particularly simple, reliable, and robust implementation.

[0014] Preferably, the in-line phase return is realized in that the phase position of the return path signal is changed by the negated measured phase of the forward path signal received at the second object relative to a phase position known relative to the local clock of the object transmitting the return path signal, in particular the phase position of its PLL.

[0015] The negated in-line phase return largely eliminates other influences, especially when repeated at different frequencies.

[0016] It is therefore preferable to determine the time deviation and / or drift based on at least two signal rounds, with different frequencies preferably being used for a second / further round than for the first / previous rounds. To determine the time deviation and / or drift, it is preferable to calculate the difference (in particular of the second order, i.e., the difference of the differences) of the phase measurements of two rounds.

[0017] Advantageously, multiple forward and return path signals are exchanged, particularly with negated and / or non-negated in-line phase return, especially at different frequencies. This makes the method not only more accurate but also more robust against environmental influences.

[0018] Preferably, the procedure is such that the phase position of a second signal received at the first object is determined at the first object and is used together with the phase position of a first signal at the first object relative to the PLL of the first object, in particular the difference in the phase positions, for time synchronization, in particular the change in the difference between two forward and return path signal pairs exchanged at different frequencies is used as a measure of the relative change of the local clocks, in particular as their relative change.

[0019] Advantageously, the determination of the time deviation and / or drift, in particular when the distance between the objects is known, is carried out radio-based by means of repeated, in particular exclusively, unidirectional signal exchange from the first to the second object, in particular on several frequencies, and on the basis of phase measurement(s) on the signal(s) received at the second object, wherein in particular the phase position of the unidirectional signal of the first object received at the second object is determined at the second object and the phase position of the first signal at the second object relative to the PLL of the second object, in particular the difference to a phase position mathematically expected for the same clocks, is used for time synchronization.

[0020] The method is advantageously performed during and / or with an approximately unchanged radio channel or with an approximately known radio channel, distance, and / or signal path length. This allows for particularly accurate results.

[0021] Particularly preferably, the relative difference, measured on received unidirectional signals at a first and a second frequency, i.e. normalized to the difference between the first and second frequency, of the phase shifts caused by the transmissions between the two unidirectional signals at the first and second frequency is used for time synchronization, in particular as a measure of the deviation of the local clocks, in particular multiplied by the proportionality factor two Pi as the deviation of the local clocks.

[0022] Advantageously, the determination of the time deviation and / or drift is carried out by determining the phase shift of the transmission of the outgoing signal from the first to the second object and the return path signal from the second to the first object by means of in-line phase return, wherein in particular the in-line phase return is realized in that the phase position of the return path signal is changed by the negated measured phase of the outgoing signal received at the second object compared to a phase position known to the local clock of the second object, in particular the phase position of its PLL.

[0023] It is particularly preferred to realize the negated in-line phase return by changing the phase position of the return path signal relative to a phase position known relative to the local clock of the object sending the return path signal, in particular the phase position of its PLL, by the negated measured phase of the forward signal received by the object sending the return path signal at the object sending the return path signal.

[0024] For particularly robust and / or precise implementation, multiple forward and return path signals are preferably exchanged with in-line phase return.

[0025] Advantageously, the procedure is such that the phase position of the second signal received at the first object is determined at the first object and is used together with the phase position of the first signal at the first object relative to the PLL of the first object, in particular the difference in the phase positions, to determine the time deviation and / or drift, in particular the change in the difference between two forward and return path signal pairs exchanged at different times and in particular at at least approximately identical frequencies is used as a measure of the frequency deviation.Preferably, the relative difference, measured at two different times on received unidirectional signals, i.e. first and second time, i.e. normalized to the difference between the first and second times, of the phase shifts caused by the transmissions between the two unidirectional signals at the first and second time is used as a measure of the deviation of the PLLs of the two objects, in particular as the deviation of the local PLLs of the objects.

[0026] Advantageously, the phase position of the unidirectional signal of the first object received at the second object is determined at the second object and the phase position of the first signal at the second object relative to the PLL of the second object, in particular the difference to a phase position mathematically expected at the same frequencies of the PLLs of the two objects, is used for time synchronization.

[0027] Depending on the design, the distance determination may preferably be a phase-based distance measurement and / or a time-of-flight based distance measurement.

[0028] Advantageously, if a relay attack is accepted and / or as a release decision, access or release is denied, a requested action or operation is not carried out and / or an alarm or blocking is carried out and / or if a relay attack is not accepted and / or as a release decision, access or release is granted and / or the requested action or operation is carried out and / or the alarm or blocking is not carried out.

[0029] To detect a relay attack, radio signals, in particular with different frequencies (f 1 , f 2 , f 3 ), are preferably transmitted between the first and second object (01, 02), and phase measurements are carried out on a first subset of the radio signals, in particular with different frequencies, and these are compared with a reference, wherein if a deviation of a predetermined value or a deviation determined from measurements on the radio signals is exceeded, a relay attack is assumed, access or release is denied, a requested action or operation is not carried out and / or an alarm or blocking is carried out and / or wherein if the deviation falls below the predetermined value or the deviation determined from measurements, in particular signal flow measurements, the absence of a relay attack is assumed,access or release is granted and / or the requested action or operation is carried out and / or the alarm or blocking is not carried out, wherein a signal propagation time measurement is carried out on a second subset of the radio signals, in particular with different frequencies, which is at least partially identical to the first subset, wherein a series of measurements is formed based on the phase measurements and / or a reference series of measurements is formed based on the signal propagation time measurements, in each case, in particular depending on the frequency of the radio signal frequencies used for the measurement, wherein the series of measurements and / or the signal propagation time measurement series advantageously either has a, in particular strictly, monotonically increasing or, in particular strictly,monotonically decreasing sequence of frequencies and wherein based on this series of measurements, a filtered and / or smoothed series of measurements is advantageously determined and / or based on the reference series of measurements, a filtered and / or smoothed reference series of measurements is advantageously determined and that the filtered and / or smoothed series of measurements, in particular its change over the frequency, is compared with the at least one signal propagation time measurement or its change and / or the reference series of measurements as a reference and / or wherein the series of measurements or its change is compared with the filtered and / or averaged reference series of measurements and / or wherein the series of measurements is compared with the reference series of measurements, in particular its change.

[0030] Subsets have, in particular, at least partially similar frequencies to one another, for example identical and / or adjacent frequencies in the radio protocol used. In particular, one frequency is similar to another if the frequency spacing for frequencies above 1 GHz is a maximum of 5 MHz, in particular a maximum of 3 MHz. In this case, at least 50%, in particular at least 90%, preferably 100%, of the frequencies of the radio signals contained in one subset and in the other of the first and second subsets contain similar and / or identical frequencies, in particular to one, in particular the smaller, of the first and second subsets, wherein each frequency of the other is only ever considered similar to a maximum of one frequency of the one, in particular when it is determined for frequencies of one whether similar or identical frequencies are present in the other.

[0031] Particularly advantageously, the method is carried out in such a way that for each measurement in one of the first or second subsets, there is a measurement in the other subset that is similar or identical in terms of frequency, in particular a similar measurement (in particular with a deviation of no more than 5 MHz) with a higher frequency and a similar measurement with a lower frequency, which was taken in close temporal proximity and / or with a largely unchanged radio channel. A largely unchanged radio channel can be ensured in particular by a close temporal proximity, whereby this depends on the movement of the objects and changes in the actual environment and changes in radio interference, in particular in relation to the wavelength. The effects should result in a phase change of less than 90° between the measurement times.As a rule, a sufficiently close temporal relationship is present if the temporal separation is less than 10 ms, especially at frequencies in the GHz range. For example, at 2.4 GHz, the wavelength is approximately 1.2 cm; assuming a maximum movement of 4 m / s (brisk jogging) = 3 cm per 7.5 ms, the temporal separation could be chosen to be less than 7.5 ms.

[0032] When a series of measurements changes over frequency, it is particularly important to consider its change over a frequency range or against the frequency, for example the gradient in a display against the frequency.

[0033] The comparison does not have to be made after conversion into distances, but the deviation can also be predetermined in other units that allow a comparison.

[0034] A conversion is particularly possible using the relationship phase shift = 2 Pi * (distance) * frequency / c, whereby it should be noted that from a certain distance onwards an ambiguity has to be taken into account and c is equal to the speed of light

[0035] RTT = 2 * distance / c and consequently, neglecting ambiguity:

[0036] Phase shift = Pi * (RTT*c) * Frequency / c

[0037] And / or dPhaseshift(f 1 ,f2) = Pi * (RTT*c) * dFrequency(f 1 ,f2) / c thus (again illustrating the ambiguity) dPhaseshift(f 1 ,f2)RT / dFrequency(f 1 ,f2) = Pi * RTT it should be taken into account that ambiguity arises at distances greater than c / dFrequency. In most applications, however, the frequency spacing can be chosen so that no ambiguities arise, at least at distances under 150 meters. In particular, the possible distance and / or the frequency difference dFrequency is / are chosen so that no ambiguity arises or that it can be neglected. In particular, the distance is smaller than the speed of light divided by the frequency difference of the phase shift measurement, in particular at least half smaller, in particular less than 300m, in particular less than 150m.

[0038] Here, phase shift(f 1 ,f 2)RT is a phase shift between the transmissions at frequencies f 1 and f 2 from one object to another and back, which occurs due to the distance. It can be approximately equated to twice the phase shift that occurs during transmission from one object to another due to the distance. Furthermore, dPhaseshift(f 1 ,f 2) is the distance-related phase shift difference, if corrected, of the radio signals received at frequencies f 1 and f 2, dFrequency is their difference, and c is the speed of light. RTT is the signal round-trip time from one object to the other and back. Instead of accepting the ambiguity problem, one can also resolve the ambiguity using other methods and formulate it by adding the determined correction term to resolve the ambiguity.

[0039] Conversions are also conceivable, for example, to a free or dimensionless quantity and / or by means of transformation, e.g., FFT. If a quantity with a new dimension is calculated for comparison using FFT, the larger subset is preferably reduced so that it has the same or a similar size, in particular one that differs by a maximum of 10%, to the smaller subset. In particular, the reduction is carried out in such a way that at least 90% of the frequency of the measurements, in particular each frequency, of the smaller subset is retained as similar as possible, whereby, in particular, only 1:1 assignments are made.

[0040] To accelerate the determination of distance and / or increase the accuracy of the determination of the distance between two objects and / or in the event of interference with reception of one of the two objects, it is desirable to perform the distance determination while largely dispensing with the radio signals of one transmission direction. The object of the present invention is to accelerate the distance determination, enable it with greater accuracy, and / or enable or improve it even in the event of interference with the radio connection on one side.

[0041] The inventor surprisingly discovered that it is possible to eliminate the need for a transmission direction between time- and / or clock-synchronized objects. This ensures faster measurements, as transceiver switching times can be largely eliminated, and enables distance determination even in the presence of severe interference on one side of the radio channel.

[0042] In particular, the distance between two objects is determined, wherein the two objects are time and / or clock synchronized to 10 ns or better, in particular in the range between 10 ns and 100 ps, ​​and wherein a first and / or second of the two objects emits signals at multiple frequencies and the second and / or first of the two objects receives these signals and, from this and the knowledge of the times of emission of features of the signals, in particular at least one feature per frequency and / or per signal, the distance between the first and second object is determined. In this case, only the first object can transmit and the second object can receive the signals from the first, or the second object can transmit and the first object can receive the signals from the second. Both can also be combined, in particular one after the other or alternately.

[0043] Signal characteristics are understood to mean, in particular, changes in the signal, such as changes in amplitude, polarization, the radiating antenna (switching between antennas), frequency, and / or phase. However, aggregated groups of characteristics can also be used, which in some situations increase the robustness of the method. For example, modulated packets or sync words can be used as groups of characteristics.

[0044] In a possible preferred embodiment, in particular for determining the distance, only the signals transmitted by the first object are used, or, in particular, exclusively, the signals transmitted by the second object. In a special embodiment, this decision can also be made individually for each frequency or for frequency groups, frequency ranges, or frequency subbands. Particularly with good or similar transmission conditions on both sides, signals from both objects can also be used at specific frequencies, frequency groups, frequency ranges, or subbands, or at all frequencies.

[0045] In a further preferred embodiment, a decision is made as to which of the signals from the first or second object will be used, in particular for determining the distance. In a special embodiment, this decision can also be made individually for each frequency or for frequency groups, frequency ranges, or frequency subbands. Particularly with good or similar transmission conditions on both sides, signals from both objects can also be used at specific frequencies, frequency groups, frequency ranges, or subbands, or at all frequencies.

[0046] This includes designs in which only the first object transmits, as well as those in which only the second object transmits, and those in which both transmit, but only a portion of the signals—namely, those sent by the first object or, in particular, those sent exclusively by the second object—are used to determine the distance. Exceptions to this are signals for time or clock synchronization, which can be used by both objects independently of the decision.

[0047] The decision as to whether the signals of the first or, in particular, the second object are used and / or which of the signals of the first or second object are used can be made before or after the signals are sent or after part of the signals are sent.

[0048] If speed is to be increased, it is preferable to make the decision as early as possible and to keep the transmission of unused signals to a minimum, especially after the decision to stop transmitting them. If the process is to be designed to be as immune to interference as possible, the decision is only made after the signals from the first and the second object have been transmitted. Transmitted and received signals can be used to make the decision. However, other data or measurements can also be used alternatively or additionally, such as noise or signals external to the process at the receiver. Knowledge of the general interference level at the location of both partners can also be used for the decision.

[0049] For distance determination, the first or, in particular, the exclusive or, of the second object are selected, whose reception at the other of the two objects was, is, or is expected to be less disturbed. In a special embodiment, this decision can also be made for each frequency individually or for frequency groups, ranges, or frequency subbands individually. Particularly in cases where transmission conditions are good or similar on both sides, signals from both objects can also be used at specific frequencies, frequency groups, ranges, or subbands, or at all frequencies.

[0050] For distance determination, the signals selected are those of the first or, in particular, the second object whose reception at the other of the two objects was, is, or is expected to be less disturbed. In a special embodiment, this decision can also be made for each frequency individually or for frequency groups, ranges, or frequency subbands individually. Particularly with good or similar transmission conditions on both sides, signals from both objects can also be used at specific frequencies, frequency groups, ranges, or subbands, or at all frequencies.

[0051] The decision is made in particular in such a way that the signals, in particular of a frequency, a frequency group or range or a frequency sub-band of the first or, in particular exclusive or, of the second object, the reception of which at the other of the two objects was, is or is likely to be more disturbed than the signals, in particular of the frequency, the frequency group or range or the frequency sub-band of the other of the two objects, are not selected and / or are not used for the determination.

[0052] The decision is made in particular in such a way that in particular the signals, in particular of a frequency, a frequency group or range or a frequency sub-band of the first or, in particular exclusive or, of the second object, the reception of which at the other of the two objects was, is or is likely to be less disturbed than the signals, in particular of the frequency, the frequency group or range or the frequency sub-band, of the other of the two objects, are selected and / or used for the determination.

[0053] If the reception of the signals from the first object and the second object is equally disrupted, in particular within a frequency, a frequency group or range, or a frequency subband, both, one, or neither of the signals can be used. The decision is preferably based on the strength of the interference, in particular compared to other frequencies, frequency groups or ranges, or frequency subbands in which the first and / or second signals were or are being transmitted. In a particularly simple embodiment, in this case, the signals from the first object are selected and / or used exclusively, or the signals from the second object, or neither of the signals are selected and / or used.

[0054] The interference can be assessed, for example, on the basis of the signal-to-noise ratio, the carrier-to-noise ratio, bit error frequency, bit error probability, symbol error frequency, bit error probability or other measurement variables or methods for assessing the signal quality or quality of the transmission channel, as is also known, for example, from EP 0 664 625 A2.

[0055] The signals are primarily radio signals.

[0056] It was also surprisingly discovered that the distances obtained from the one-sided distance measurement described here or according to the invention, when using commercially available transceivers such as the somewhat older cc2500 or the current cc26xx from Texas Instruments, the Kw35 / 36 / 37 / 38 from NXP, or the DA1469x from Dialog, depend on the frequency used for distance determination. Inaccuracies in the transceivers also appear to lead to calculated distances below the actual distance, but only at frequencies whose transmission channel is strongly attenuated, so these can easily be eliminated from the calculation.

[0057] Thus, when determining distance, it is advantageous to partially exclude signal components of the object whose signals are used for distance determination, specifically those components that are above an upper power limit and / or those components that are below a lower power limit. These limits can be predetermined or determined from the received signals and, in particular, can be above or below the average received power, and in particular, at least 20% above the average received power (upper power limit) and / or at least 20% below the average received power (lower power limit).

[0058] Preferably, signal components at frequencies with less than 40% or at least signals with less than 20%, in particular less than 40%, of the average energy of the signals and / or signals with more than 140%, in particular more than 120%, of the average energy received are not taken into account.

[0059] Advantageously, the lower power limit is in the range of 5 to 50% of the average power of the received signals and / or the upper power limit is in the range of 120 to 200% of the average power of the received signals.

[0060] In another embodiment, from the signals selected in particular in the decision, the x% of the signals with the smallest received amplitude are sorted out and not used, and / or the y% of the signals with the largest received amplitude are sorted out and not used. It has proven particularly advantageous if the sum of x and y does not fall below 10 and / or does not exceed 75 and / or x is in the range from 10 to 75 and / or y is in the range from 20 to 50. With these values, high accuracy and reliable distance determination can be achieved in most situations.

[0061] Advantageously, the second or, in particular, exclusive or, first object does not send any signals for distance determination and / or the second or the first object, in particular, exclusive or, sends signals only for time and / or clock synchronization. This allows for energy and processing time savings.

[0062] Preferably, the first and / or second, or each of the two, objects transmits the signals on multiple frequencies consecutively and / or one after the other, particularly immediately after the other. In particular, when transmitting by the first and second objects, all signals from the first or second object are transmitted first, followed by those from the other. This allows, among other things, the influences of environmental or distance changes and of movements of one or both objects to be reduced.

[0063] Advantageously, the signal bandwidth never exceeds 50 MHz, especially 25 MHz. This saves energy, avoids interference with other processes, and allows for the use of simpler components compared to broadband methods.

[0064] Preferably, at least one time and / or clock synchronization and / or correction between the two objects is performed before, after, and / or during the execution of the method. This increases the accuracy of the method. Preferably, a drift of the clock of the first and / or second object, or a difference in the drift of the clocks of the first and second objects, is also determined and taken into account when determining the distance. This increases the accuracy of the method.

[0065] Advantageously, the method is carried out such that the frequency spacing between two consecutive frequencies of the plurality of frequencies is at least 0.1 MHz and / or a maximum of 10 MHz, and / or the plurality of frequencies represent at least five frequencies and / or a maximum of 200 frequencies, and / or wherein the plurality of frequencies span a frequency band of at least two MHz and / or a maximum of 100 MHz. This allows a balance to be found between bandwidth requirements, which place demands on available frequencies and hardware, and accuracy.

[0066] Preferably, the method is carried out in such a way that the accuracy of the distance determination is in the range of 0.3 m to 3 m, in particular at least for distances in the range of 0 to 50 m. In these ranges, the advantages of the invention are particularly evident.

[0067] Advantageously, the distance determination is based on determining the signal propagation time from the first to the second or from the second to the first object and / or on determining the phase shift of the signals from the first to the second or from the second to the first object. The component of the shortest signal path (the shortest distance detectable in the signal) can also be searched for in the received signal using FFT and / or high-resolution methods such as MUSIC or CAPON. For this purpose, the signal components of the shortest path between the two objects (in particular the transmitter and receiver) are isolated using FFT and / or high-resolution methods, and only these are used for further processing, in particular for phase measurement.

[0068] Advantageously, for each signal received at the second and / or first object, a value proportional to its amplitude and a phase value are determined, and in particular a complex number is determined therefrom, which is used to determine the distance between the first and second objects. The phase value is determined in particular by calculating, for a plurality of pairs of signals with adjacent frequencies, a phase shift change normalized to a frequency spacing, i.e., by approximately calculating the derivative of the phase shift at one of the frequencies of the pair, and using the values ​​collected in this way to determine the phase and / or the argument of the complex number at the respective frequency (the value corresponding to the amplitude-proportional value), in particular by approximate integration over the frequency.The integration does not have to start at f = 0 Hz; instead, an offset common to all phases and / or complex numbers can and is preferably used, in particular the lowest frequency of the signals, especially the selected ones. In particular, the phase value and / or the argument of the complex numbers is determined from the signal propagation time or signal round-trip time.

[0069] In particular, the normalized phase shift change (dPhaseshift(f 1 ,f2)) is obtained using the formula: dPhaseshift(f 1 ,f2) = a * RTT(f3) * dFrequency(f 1 ,f2) where dFrequency(f 1 ,f2) is the difference between the frequencies f1 and f2

[0070] RTT(f3) is twice the signal propagation time or the signal round trip time between the first and second object at one or more frequencies f3, similar to f1 and / or f2 and / or vice versa and where a is a constant, in particular equal to two Pi.

[0071] The complex value Z for a frequency is then determined in particular by:

[0072] Amount(Z(f)) = (b* Amplitude(f) + offset)

[0073] Argument(Z(f)) = Sum(dPhaseshift(f 1 ,f2) * dFrequency(f 1 ,f2)) over f1 from f0 to f

[0074] The phase shift changes are therefore summed up with the frequency intervals, from the lowest frequency to the frequency in question for which the complex number is to be determined.

[0075] Where b and offset are constants and b is in particular 1 and offset is in particular 0. Amplitude(f) is the received amplitude measured at frequency f or an average of several amplitudes measured at frequency f and / or frequencies similar to f.

[0076] The phase shift is the phase shift in the frequency transmission from one object to another and back, which occurs due to distance. It can be approximately equal to twice the phase shift that occurs in the frequency transmission from one object to another due to distance.

[0077] In particular, a matrix, in particular an autocorrelation matrix, is formed from a plurality of complex numbers, and the distance is determined using known methods, for example, MUSIC, CAPON, comparison with, distance calculation to, and / or projection onto radiation and / or reception characteristics. The distance is advantageously calculated using the eigenvalue or eigenvector determination of the at least one matrix and / or Fourier transformation of the complex values. Such procedures are particularly advantageous in multipath signal propagation to achieve a reliable determination.

[0078] But even independent of the use of complex numbers, autocorrelation matrices, etc., it is advantageous to work with differences in phase shifts between measurements at different frequencies when determining distances, as this avoids other influences. For example, using dPhaseshift = 2 Pi * (2*Distance) * dFrequency / c, the distance between objects can be easily determined using the difference in the phase shifts during two signal roundtrips between the two objects, once at a first frequency and once at a second frequency with the frequency separation dF.The same can also be applied for unidirectional signal exchange or when using signals only via the forward or return path between the first and second object: dPhase shift(from the first to the second object) = 2 Pi * (distance) * dFrequency / c pder dPhase shift(from the second to the first object) = 2 Pi * (distance) * dFrequency / c.

[0079] It is advantageous to calculate an average value from several distance measurements and / or to average the measurements to determine a distance value.

[0080] If positioning is desired, it is advantageous to carry out the method according to the invention between a plurality of pairs of objects, wherein, in particular, one object in each pair is an object that is involved in all pairs, and wherein the determined distances between the pairs are used to map and / or determine the position of at least one of the objects. In particular, it is advantageous to perform these pairwise measurements simultaneously.

[0081] The problem is also solved by one or two objects or systems, each equipped with transmitting and receiving means and a controller, equipped to carry out the method according to the invention.

[0082] The objects are advantageously parts of a data transmission system, in particular a Bluetooth, WLAN, or mobile radio data transmission system. The signals are preferably signals of the data transmission system, in particular of a data transmission standard, for example, a mobile radio standard, WLAN, or Bluetooth, which are used for data transmission in accordance with the data transmission standard.

[0083] Advantageously, the signals are transmitted via a plurality of antenna paths, in particular at least three, in particular with a plurality of antennas, in particular one after the other, at the transmitting object and / or received with a plurality of antennas at the receiving object.

[0084] The calculation is performed, for example, as follows: When averaging the measured distances, measurements of received signals with less than, for example, 40% of the average energy of the received signals are ignored. This excludes measurements at frequencies with a strongly attenuated transmission channel.

[0085] The exact time difference and time drift between the two objects are also determined and the reception times of features of the signals whose transmission times are known are measured on n > 1 frequencies.

[0086] The results can be used to determine the distance in various ways, for example:

[0087] Calculation 1: The sum (RTTASUM) of all signal propagation times before summation is multiplied by the respective amplitude, and the sum (ASUM) of all amplitudes is calculated. Dividing RTTASUM by ASUM then provides a useful estimate of the signal propagation time, from which a distance can be easily determined.

[0088] Calculation 2

[0089] All measurements with a received amplitude less than 40% of the average received amplitude are discarded. Of the remaining signal propagation times, the 20% smallest signal propagation times and the 50% largest signal propagation times are discarded.

[0090] The remaining 30% of the signal propagation times are averaged, allowing a distance to be determined directly.

[0091] Calculation 3

[0092] All signal round trip times or double signal transit times (RTT) are converted into a phase shift difference or phase shift derivative: dPhase shift = 2 Pi * (2*distance) * dFrequency / c

[0093] RTT = 2 * Distance / c dPhase shift = 2 Pi * (RTT*c) * dFrequency / c

[0094] Here, dPhase shift is a distance-dependent phase difference between two frequencies that are spaced by dFrequency or a difference between two distance-dependent phase shifts between transmissions between two frequencies that are spaced by dFrequency, c is the speed of light.

[0095] Then the calculated phase shift changes are summed: sumPh(Fn) = sum dPhase shift (FO...Fn) FO to Fn are the multiple frequencies.

[0096] These summed dphase shifts, each as an argument of a complex number with the corresponding amplitudes determined during reception or proportional values ​​as the magnitude of the complex numbers, can then be input as complex values ​​into a Fourier transform, or they can be used to perform a spectral estimate in matrices using super-resolution methods (e.g., MUSIC or CAPON). The spectrum is then the spectrum of paths of varying length that the signal travels before arriving superimposed at the receiving antenna. In this case, it is particularly advantageous to use multiple antenna paths during transmission and to include them in the evaluation.

[0097] For time synchronization and / or determination of a deviation between timers, but alternatively or additionally also for frequency synchronization and / or determination of a frequency deviation of local PLLs of the objects, within the scope of this method, however, also on its own as a separate invention between two objects (e.g. first and second anchor), in particular with a known phase relationship of the transmitted signals and / or PLLs, in particular in each case relative to the respective local timer of the respective transmitting of the two objects, preferably also with an in-line phase return, wherein the addition known for distance determination is replaced by a subtraction (negated in-line phase return).This enables particularly fast execution of the synchronization and / or detection, especially when the distance and / or the radio signal path length(s) between the two objects is known and / or constant, but when repeated at different frequencies even without knowledge of the distance.

[0098] For this purpose, in particular a radio signal with a first frequency is transmitted from the first object to the second object and the second object responds by transmitting a second radio signal, in particular also with approximately the first frequency, to the first object. This signal round is preferably repeated, but with a second frequency different from the first frequency. In particular, the repetition occurs multiple times, in particular with multiple frequencies, wherein the frequency spacing between two of the multiple frequencies which follow one another in terms of frequency and / or time sequence is at least 0.1 MHz and / or a maximum of 10 MHz and / or the multiple frequencies represent at least five frequencies and / or a maximum of 200 frequencies and / or wherein the multiple frequencies span a frequency band of at least two MHz and / or a maximum of 100 MHz.

[0099] Preferably, the transmitted received radio signal is broken down into signal path components, and for the following determinations, one or more signal path components are always considered separately, in particular one or more whose radio signal path length is known. Alternatively or additionally, known methods can be used to attempt to reduce multipathing, for example, by appropriately selecting frequencies.

[0100] For example, if the phase positions relative to the local clocks of the two objects are known—that is, the phase position of the PLL or the transmitted signals of the first object relative to the clock on the first object and the phase position of the PLL or the transmitted signals of the second object relative to the clock on the second object—the synchronization of the two clocks can be achieved quickly and easily using (negated) in-line phase return. This also allows the frequency deviation of the PLLs of the two objects to be determined.

[0101] The frequency deviation of the PLLs of the two objects (CFO crystal frequency offset), which can be used directly for frequency synchronization, can be determined, for example, using the following procedure:

[0102] CFO = 1 / 2* ddPhase(t2,t1 ) / (2*Pi) / (t2-t1 ), where ddPhase(t2,t1 ) is the measured change between the phase shifts of two response signals from the second object (difference of the second straight line), where the second object has sent these two response signals to the signals sent at the first object at time t1 and at time t2 of the timer on the first object (one to the one sent at time t1 and one to the one sent at time t2) and these two response signals were received at the first object and where the second object, when sending the response signals, has already subtracted the phase of the signals sent at times t1 and t2, which it had previously received, from the phase position which is known relative to the timer of the second object (negated in-line phase return).The phase shift is the phase shift caused by the radio channel and / or the transmission of the signals (during round trip (one signal from the first object to the second and from the second to the first) with negated in-line phase return). The change in the phase shift is then to be understood in particular as the change in the phase shift from the first (starting at t1) to the second (starting at t2) round trip with negated inline phase return, i.e. the difference of the second straight line.

[0103] The signals of a round trip advantageously have similar, in particular approximately identical, frequencies. Approximately identical frequencies exist in particular when they are considered identical due to the existing synchronization, their deviation is not greater than the current CFO, and / or their difference does not exceed 100 MHz.

[0104] A longer time interval between the round trips and / or t1 and t2 results in greater accuracy and is therefore preferable. It is important to ensure unambiguousness at (2 * Pi) / 2. Depending on how accurately the CFO was known prior to the measurement, the time interval between the round trips can be optimized to be large while still maintaining unambiguousness. In practice, particularly with an existing CFO of 100 Hz or better (lower), time intervals between t1 and t2 or the round trips in the range of 0.3 to 50 ms have proven to be effective. Preferably, subsequent measurements with increasing time intervals are performed, taking into account the accuracies achieved based on the previous measurement(s), in order to keep the time intervals as large as possible while maintaining unambiguousness.Preferably, the frequencies of the signals transmitted at time t1 and time t2 of the timer on the first object are selected to be identical, and the frequencies of the response signals of the second object to the signal transmitted at time t1 and to the signal transmitted at time t2 of the timer on the first object are also selected to be identical, in particular approximately identical to the frequencies of the signals transmitted at time t1 and time t2 of the timer on the first object. This means that they were aligned, in particular, as far as possible with the available information and resources.

[0105] With sufficient time synchronization accuracy and a known distance and / or signal path length, the method can also be performed unidirectionally, even with only one signal at a single frequency. If a signal with a certain frequency and a known phase position is emitted at the first object at a known time, the expected phase position at the second object can be calculated. If the actual phase position is measured, the CFO can be calculated from this. However, all errors related to the signal path length and time synchronization, as well as phase measurement, directly influence the determination of the CFO. Therefore, this method is used primarily as a supplement to the inventive time synchronization.

[0106] The method is preferably repeated at several different frequencies (e.g. fa and fb) at different times (e.g. ta for the start of execution at fa and tb for the start of execution at frequency fb; t1 is then in particular equal to ta in each case). Preferably, the frequencies have no linear distances from the time of execution (e.g. ta and tb) or only a low linear dependence, in particular of less than 10%. A low linear dependence is given in particular when the two-dimensional vectors, each consisting of frequency and transmission time, have a linear component of less than 10% to one another. This is the case, for example, in pairs between two such vectors if the projection of one onto the other has a length of less than 10% of the length of one.Thus, especially with fb - fa = Kab * (tb - ta) for different pairs of fa and fb, Kab is not the same for all pairs, but in particular, it is different for all pairs. In another preferred, but technically more complex embodiment, the implementation is carried out at multiple frequencies simultaneously.

[0107] The time difference (dT), which can then be used directly for synchronization, can be determined using the following calculation: dT = 1 / 2* ddPhase(f2,f1 ) / (2*Pi) / (f2-f 1 ), where ddPhase (difference of the second straight line) is the measured change between the phase shifts of two response signals of the second object, where the second object has sent these two response signals to the signals sent by the first object with the frequency f1 and frequency f2 (first signal at f 1 , second signal at f 2 ) and these two response signals (one to the one at f1 with approximately also frequency f1 and one to the one at f2 with also approximately frequency f 2 ) were received at the first object and where the second object, when sending the response signals, has already subtracted the previously received phase of the signals sent by the first object from the phase position known relative to the timer of the second object (negated in-line phase return),In particular, the transmitted phase of the response signals has been rotated by the negative received phase of the previously received signal. A response signal is the response signal sent to the signal transmitted at frequency f1, and a response signal is the response signal sent to the signal transmitted at frequency f2.

[0108] The measurement of the runout of the first signal at f1 and the corresponding response signal, and the measurement of the runout of the second signal at f2 and the corresponding response signal, are advantageously performed at a time interval during which the channel has not changed significantly, especially simultaneously. A CFO also leads to deviations if the measurements are not performed simultaneously. While the deviation can be mathematically calculated with an approximately known CFO, it is advantageous to avoid or minimize it. In practice, a time interval of a maximum of 100 ms has proven effective.

[0109] Advantageously, signals for determining the frequency deviation and / or frequency synchronization are also used to determine the time difference and / or time synchronization, or vice versa. For this purpose, frequency hopping is used, in particular with non-equidistant frequency intervals and / or frequency intervals that are small or non-linear compared to the transmission time. In particular, this method is thus used for determining the frequency deviation and / or frequency synchronization on the one hand, and for determining the time difference and / or time synchronization on the other.

[0110] Preferably, the methods are repeated individually or jointly for several different frequency pairs (e.g., several pairs of fa and fb) at identical or different times (e.g., ta1 for the start of execution at fa 1 and fb 1, and ta2 for the start of execution at frequencies fa2 and fb2). Preferably, the frequencies and / or frequency differences exhibit little or no linear dependence on the time of execution.

[0111] It is therefore true, in particular with (fb 1 - fa 1 ) / (fb2 - fa2) = K1 2 * (ta1 - ta2) for different pairs of pairs fan / fbn and fam / fbm, that Knm is not the same for all, in particular it is different for all pairs of pairs.

[0112] In another preferred, but technically more sophisticated embodiment, the implementation is carried out for several pairs of frequency pairs simultaneously.

[0113] In a preferred embodiment, the radio signal exchange between the anchors / objects for time synchronization occurs in a manner that allows for rapid switching between the transmission frequencies, particularly relative to the time required to turn the transmission amplifier on and off, such that first one object (e.g., the first anchor) transmits, particularly sequentially, on different frequencies, and then another object (e.g., the second anchor) transmits, particularly sequentially, on different frequencies. This allows the required time to be reduced.

[0114] In another preferred embodiment, the radio signal exchange between the objects for time synchronization occurs in which a slow switching between the transmission frequencies is provided, particularly in relation to the time required for switching the transmission amplifier on and off, so that the objects transmit only one signal at a time on one frequency, thus always alternating. This can reduce the required time.

[0115] In a further preferred embodiment in which the, in particular ongoing, time synchronization of the objects / anchors, in particular after an initial (possibly also arbitrary) time synchronization, with and / or during an approximately constant radio channel (reference channel) (e.g. if the average distance of the transmitted energy of the radio channel changes by less than 1 m, in particular by less than 10 cm, during and / or during the time synchronization and / or the time synchronization is carried out in such a way that this condition is met) between the anchors can be carried out radio-based, this is preferably carried out in such a way that the, in particular ongoing, time synchronization takes place between two anchors, in particular multiple times and continuously, by means of unidirectional signal exchange on several frequencies and on the basis of phase measurements on the exchanged unidirectional signals.

[0116] This can be done, for example, using the following calculation:

[0117] If dPh(F2,F1 ) is the relative (i.e. normalized to the difference of the frequencies F1 and F2) change in the phase shift (difference of the second degree of the phase shift) (caused by the transmission channel) between the two unidirectional signals at F1 and F2 measured on received unidirectional signals at frequencies F1 and F2, for example from the first to the second anchor, then ddPh((F2,F1 ),t2, t1 ) is the relative phase shift difference, i.e. the phase shift measured at time t2 corrected for the effect of the transmission channel, i.e. ddPh((F2,F1 ),t2, t1 ) = dPh(F2,F1 )(t2) - dPh(F2,F1 )(t1 ) with dPh(F2,F1 )(t2) as dPh(F2,F1 ) of a signal at time t1 and dPh(F2,F1 )(t1 ) as dPh(F2,F1 ) of a signal sent or received at time t2, then ddPh() is proportional to the shift dT of the time base between the objects / anchors between times t1 and t2.

[0118] So the time shift dT can be calculated with: dT = ddPh((F2,F1 ),t2, t1 ) / (2*pi) / (F2-F1 )

[0119] For this purpose, the change in the measured phases, in particular phase shifts, is preferably considered, especially at a plurality of frequencies, with the "reference measurement" with known time synchronization (t1). By measuring at different frequencies, the spacing of which is preferably selected to be large, in particular in the range of 50 - 500 MHz, a particularly error-tolerant determination can be made, which in particular places lower demands on the CFO and the previously existing coarse time synchronization and yet quite reliably avoids the ambiguity problem because, so to speak, a virtual measurement is only carried out at the difference frequency. For example, if the measurement is carried out in the 2.4 GHz band with the frequencies 2400 and 2480 MHz, the difference is only 80 MHz.Then 12ns corresponds to 360° phase rotation, so that with a phase measurement accuracy in the range of + / -3 to 6° a fairly good time synchronization can be achieved and this with only low requirements in terms of avoiding ambiguity problems regarding the phase position.

[0120] The rate of change of the time synchronization from time t1 to time t2 is then: ddT = dPh at time 2 - dPh at time 1 = ddPh((F2,F1),t2, t1) / (t2 - t1). ddPh((F2,F1),t2, t1) can also be replaced by an average of several ddPh((Fn,Fm),t2, t1) with several frequency pairs Fn,Fm. This can increase the accuracy. ddPh is therefore the change in the phase shift measured at the second object (previously adjusted for the phase shift caused by the transmission channel) between signals received at the second object that were transmitted at the first object at times t1 and t2.

[0121] With sufficient accuracy of the measurement setup, in particular a sufficiently well-known signal path length, a sufficiently small CFO, and sufficiently accurate phase measurement, the time deviation can also be easily determined using a unidirectional signal. If a signal with a known phase position is emitted from the first object at a given frequency and its phase position is determined at the second object, this can be compared with the expected phase position, and dT can be directly determined from the deviation. However, this requires high accuracy requirements, especially at high frequencies, to avoid ambiguity.

[0122] Sufficient accuracy is achieved when ambiguity in the phase measurement can be reliably avoided. This can be determined mathematically based on the frequency used.

[0123] In general, the frequencies used in this text are preferably above 2 GHz. This allows for high accuracy and allows the use of existing transmitters, such as Bluetooth, Wi-Fi, and / or mobile networks, such as LTE.

[0124] Advantageously, the objects, or at least some of the objects, constitute an anchor network. Thus, an infrastructure for locating objects can be easily created using the anchor network, whose anchors synchronize their time with each other and whose distances, in particular at least their relative positions, are determined / known. Advantageously, the distance between the anchors / objects and / or their relative position is determined using radio-based distance measurements between any two of the anchors / objects. This completely eliminates the need for other measurement methods, such as manual or light-based ones. This reduces the amount of equipment required. Furthermore, it enables the quick and easy setup of, for example, ad hoc, anchor networks. This can be helpful, for example, in emergency situations to locate a radio node, such as a cell phone.In this way, a group of people, each carrying a radio node, for example in the form of a mobile phone, can set up an anchor network in the event of the loss or burial of one of the people using the radio nodes of the remaining people, and the radio node of the lost or buried person can be located promptly. For this purpose and in general terms, the radio nodes can, for example, determine their relative position using GPS and / or radio-based distance measurement. After an initial determination, the position of some or all of the anchors can be adjusted in order to improve the determination in a subsequent implementation of the method. This allows precise location to be achieved very quickly and reliably. For this purpose, the position of the anchors is changed, in particular iteratively, so that they are arranged around the radio node to be located, in particular evenly.For this purpose, some or all anchors can move to the approximate position between measurements, in particular from different sides, while maintaining a, in particular predetermined, minimum distance between the anchors of, for example, 2 m.

[0125] It is preferred if the armatures adjust the phase of the emitted signals based on a time difference between the armatures so that the signals from the armatures appear to be emitted coherently. In a simple embodiment, the armatures transmit their signals at times fixed relative to their respective local clocks; this leads to deviations due to drift even with time synchronization. However, known phase jumps during switching and different phase positions of the radiation from different armatures can also result in an armature system viewed from the outside appearing incoherent. This can be changed by slightly changing the switching times so that the armature system appears coherent from the outside, at least from a certain distance from each armature. This can then simplify the necessary calculations.

[0126] With particular advantage for easy installation, the anchors or some of them are part of, in particular, stationary loudspeakers and / or lamps and / or other electrical infrastructure installed or operated in buildings or rooms (also: sockets, switches, smoke detectors, etc.).

[0127] To improve the accuracy and robustness of the method, the radio node (an object) communicates with the at least two anchors (each also an object) via multiple antenna paths and / or the anchors, or more abstractly two objects, communicate with each other in pairs via multiple antenna paths. An antenna path is, in particular, the radio channel from a first transmitting antenna to a first receiving antenna. If, for example, two antennas are used for reception, for example of an object, e.g. an anchor, and the signals received with them are evaluated separately, two antenna paths are used. If, for example, a second transmitting antenna, e.g. of the radio node, is also used later in time, and reception is carried out with the two receiving antennas, four antenna paths are used.

[0128] In certain use cases, it is preferable to build an anchor network of mobile devices ad hoc, with the anchors first determining information about their relative positioning and synchronizing frequencies and / or times, especially repeatedly. This allows for a rapid, solid anchor network and determination. This is possible with active and / or passive radio nodes.

[0129] Generally, depending on the application, it is preferable to work with active and / or passive radio nodes. Passive radio nodes are advantageous, for example, when a large number of radio nodes are used simultaneously and / or the radio node(s) should remain anonymous and / or undetected. The use of active radio nodes can be advantageous when they should consume as little electrical power as possible, i.e., transmit only briefly and receive for a short time. Combining active and passive provisions for a radio node can utilize the advantages of both variants.

[0130] Regarding the in-line phase return, the following considerations are helpful for understanding

[0131] On a tone (i.e. a frequency f) the measured phase shift in the

[0132] Recipient (Ph):

[0133] Ph = const + dt * f + s / lambda const is the phase difference between the two PLLs of objects A and B. Where: dt: the time deviation of the timers of objects A and B - the formula does not take time drift into account s: constant distance between the objects lambda: wavelength at frequency f

[0134] The phase shift (PhA) and PhB) at the receiving objects A and B is then:

[0135] PhA = const + dt * f + s / lambda

[0136] PhB = -const + -dt * f + s / lambda

[0137] This means that the sum of the phase shifts of the two objects A and B on the same note is:

[0138] PhA + PhB = const + dt * f + s / lambda - const - dt * f + s / lambda

[0139] PhA + PhB = 2 * s / lambda

[0140] In this way, the distance s can be determined, particularly preferably with non-negated in-line phase return.

[0141] The difference in phase shifts between the two objects A and B on the same tone is (without drift and at constant distance): PhA - PhB = const + dt * f + s / lambda + const + dt * f - s / lambda

[0142] PhA - PhB = 2 * const + 2 * dt * f

[0143] With a known PLL offset (constant), the time offset can be determined, especially with negated inline phase return, and used for correction. Repeating this process at a different time point also allows the relative drift of the timers to be determined.

[0144] If the method is carried out, in particular with negated in-line phase return, on two different frequencies, for example a first signal round trip at f1 and a second at f2, and if the phase shift difference of the second straight line is formed, in particular realizable by negated in-line phase return, one obtains

[0145] PhA(f1 ) - PhB(f 1 ) - (PhA(f2) - PhB(f2)) = 2 * const + 2 * dt * f1 - 2 * const - 2 * dt * f2

[0146] PhA(f1 ) - PhB(f 1 ) - (PhA(f2) - PhB(f2)) = 2 * dt * f1 - 2 * dt * f2

[0147] PhA(f1 ) - PhB(f 1 ) - (PhA(f2) - PhB(f2)) = 2 * dt * (f 1 - f2)

[0148] Can also be represented as dT = [PhA(f 1 ) - PhB(f 1 ) - (PhA(f2) - PhB(f2))] / 2 / dF

[0149] If the difference in frequencies is known, the time offset can be determined easily and reliably. If the time difference is known, the frequency difference can be determined reliably and easily.

[0150] This can be further simplified using a negated inline phase return, since

[0151] PhA(f1 ) - PhB(f1 ) can be determined directly by measurement (Mf1 ) at the end of the run, as can PhA(f2) - PhB(f2) ( = Mf2).

[0152] This yields dT = ddPh / 2 / dF with ddPh = Mf1 -Mf2 (difference of the second straight line of the phase shift). The following explanations explain the inventions purely by way of example using the purely schematic figures. The figures show:

[0153] Fig. 1 shows an example of two possible procedures,

[0154] Fig. 2 an illustration of an anchor network and an active

[0155] radio stations,

[0156] Fig. 3 an illustration of an anchor network and a passive

[0157] Radio control and

[0158] Fig. 4 an illustration of time synchronization using in-line phase return.

[0159] Figure 1 shows two possible procedures purely schematically, not restrictively, and merely as examples. In the left column, the decision is made only after the signals from the first and second object have been transmitted, while in the right column, this occurs before the signals are transmitted, and only one of the objects transmits the signals. What both have in common is that the calculation or determination of the distance only considers the signals from one of the objects.

[0160] Figure 2 shows an anchor network with two anchors A1, A2 with fixed positions and a known distance. The radio node FK transmits unidirectional signals, which are received by the anchors A1, A2. From this, the difference between the distances represented by double arrows is determined. If the method is performed with multiple anchors, for example, three or four, and their positions are known, the position of the radio node can be determined in two or three dimensions.

[0161] Figure 3 shows an anchor network with two anchors A1, A2 and a passive radio node FK, which receives the unidirectional signals from anchors A1, A2 and determines the difference in the distances represented by double arrows. If the method is performed with multiple anchors, for example, three or four, and their positions are known, the position of the radio node can be determined in two or three dimensions.

[0162] Figure 4 shows an illustration of time synchronization by means of negated in-line phase return between two objects A1, A2, which can be anchors of an anchor network. The objects each have local timers and each have a PLL, which are preferably set to approximately the same frequencies, the phase position of which is known in relation to the respective local timer of the object, but is assumed here for simplicity to be identical, and the phase of which for each anchor is shown at two times Ta, Td for object A1 and Tb, Tc for object A2 by pointers in a circle, the outer circle in each case. The pointers in the inner circles (A1 right, A2 left) show the phase of a signal. The arrows between the objects illustrate signals, the upper one a first from the first object A1 to the second object A2 and the lower one a second from the second object A2 to the first object A1.The first object sends a signal starting at time Ta with the phase position of the internal PLL, so the pointers are identical. This signal start is received at the second object at time Tb, with a phase position indicated by the upper left pointer, while the internal PLL of the second object A2 has the phase indicated by the pointer in the upper right. The second object starts sending the second signal at time Tc, which for the sake of simplicity has been assumed to be approximately equal to Tb. This signal would be sent with the phase of the PLL without in-line phase return. For the negated in-line phase return, however, it is now rotated by the negated deviation of the received first signal to the PLL of the second object and thus starts sending with a different phase position, illustrated by the lower left pointer in the second object.The first object receives the signal and determines the phase position of the signal's start relative to its own PLL. From this, combined with the phase of the first signal's start of transmission, it can determine the phase shift through the radio channel of the round trip. The signal start does not necessarily have to be used as the temporal reference point. If the distance is constant and known, the deviation of the objects' clocks can be determined, for example, using the formula explained above.

[0163] PhA - Phß = 2 * const + 2 * dt * f

[0164] If the distance is constant, the deviation of the timers of the objects can be determined by repetition, even without knowing the distance, for example using the formula explained above: dT = ddPh / 2 / dF

Claims

Claims 1 . Method for determining distance by means of radio signals or detecting relay attacks, in particular for determining distance by means of radio signals, between two objects, each having a timer, wherein the two objects emit radio signals on several frequencies and the radio signals are received by the non-transmitting of the two objects, and the receiving object carries out at least one measurement of the phase and / or at least one measurement of the signal arrival time and / or the signal propagation time relative to its timer for each frequency and / or radio signal and responds thereto by emitting at least one radio signal, in particular on the same frequency,wherein the non-responding object of the two objects receives the at least one radio signal emitted in response and carries out at least one measurement of the phase and / or at least one measurement of the signal arrival time and / or signal propagation time relative to its timer for each frequency and / or radio signal, and from this at least one determination of the phase shift and / or at least one determination of the signal propagation time for each frequency is made, and based on the at least one determination, an evaluation is carried out which, in particular, determines the distance between the first and second objects and / or determines whether a relay attack is present and / or makes a release decision, wherein the method includes a determination of a time deviation between the timers of the objects, and in particular also of at least a relative drift of the timers of the objects, and the method includes a decision at least for each frequency and / or each signal round-trip period,whether the measurements on the at least one signal of the first and / or second object are used for the distance determination and / or the detection, wherein the decision is made in particular on the basis of at least one estimation or determination of the effects of interference on the reception at both objects, in particular their ratio and / or difference, in particular on the basis of amplitudes, channel and / or Measurement quality indicators, whereby for the distance determination and / or detection the selected measurements are corrected for the influence of the determined time deviation and the determined drift.

2. Method according to claim 1, wherein at least one difference is determined between each two phase shifts caused by a transmission between the two objects or by a signal round trip, which in particular form different signal round trips, between the two objects, wherein the transmissions or / or, in particular different, signal round trips are carried out with signals of different frequencies and wherein the distance determination, the detection of relay attacks and / or the determination of the time deviation is based on this at least one difference, in particular each of its ratios to the difference in the frequencies of the signals used to determine the respective one of the at least one difference.

3. Method according to claim 1 or 2, wherein the method is carried out in such a way that, in order to determine the time deviation and / or drift, the relative phase position of two radio signals of different frequencies is known by means of the PLL of an object as a function of the time difference of the generation or emission of the two signals at one of the objects relative to its timer and / or the phase position of the PLL of each of the objects at different frequencies is known relative to its timer, wherein the determination of the time deviation and / or drift between the objects is carried out radio-based by means of phase measurement(s) on a plurality of the radio signals of different frequencies transmitted between the two objects.

4. Method according to one of claims 1 to 3, wherein the determination of the time deviation and / or drift is carried out by determining phase shift the transmission of the outgoing signal from the first to the second object and the return signal from the second to the first object is carried out by means of in-line phase return.

5. The method according to claim 4, wherein the in-line phase return is realized in that the phase position of the return path signal is changed at the second object relative to a phase position known relative to the local clock of the second object, in particular the phase position of its PLL, by the negated measured phase of the forward path signal received at the second object.

6. Method according to one of the preceding claims, wherein multiple forward and return path signals, in particular with in-line phase return, are exchanged between the objects, in particular at different frequencies.

7. Method according to claim 1 to 6, wherein the phase position of a second signal received at the first object is determined at the first object and is used together with the phase position of a first signal at the first object relative to the PLL of the first object, in particular the difference in the phase positions, for time synchronization, in particular the change in the difference between two forward and return path signal pairs exchanged at different frequencies is used as a measure of the relative change of the local clocks, in particular as their relative change.

8. Method according to one of claims 1 to 4, wherein the determination of the time deviation and / or drift, in particular when the distance between the objects is known, is carried out radio-based by means of, in particular at different frequencies, repeated, in particular exclusively, unidirectional signal exchange from the first to the second object, in particular on several frequencies, and on the basis of phase measurement(s) on the signal(s) received at the second object, in particular wherein the phase position of the unidirectional signal received at the second object signal of the first object at the second object is determined and the phase position of the first signal at the second object relative to the PLL of the second object, in particular the difference to a phase position mathematically expected for the same clocks, is used for time synchronization.

9. Method according to one of claims 1 to 8, wherein the method is carried out during and / or with an approximately unchanged radio channel or with an approximately known radio channel, distance and / or approximately known signal path length.

10. The method according to claim 8 or 9, wherein the relative difference in the phase shifts caused by the transmissions, measured on received unidirectional signals at a first and a second frequency, i.e. normalized to the difference between the first and second frequency, in particular when using the negated in-line phase return, between the two unidirectional signals at the first and second frequency for time synchronization, is used in particular as a measure of the deviation of the local clocks, in particular multiplied by the proportionality factor two Pi as the deviation of the local clocks. 1 1. Method according to one of claims 1 to 10, wherein the determination of the time deviation and / or drift is carried out by determining the phase shift of the transmission of the outgoing signal from the first to the second object and the return path signal from the second to the first object by means of in-line phase return, wherein in particular the in-line phase return is realized in that the phase position of the return path signal is changed by the negated measured phase of the outgoing signal received at the second object compared to a phase position known from the local clock of the second object, in particular the phase position of its PLL.

12. Method according to one of the preceding claims, wherein multiple forward and return path signals are exchanged with in-line phase return.

13. Method according to one of claims 1 1 to 12, wherein the phase position of the second signal received at the first object is determined at the first object and is used together with the phase position of the first signal at the first object relative to the PLL of the first object, in particular the difference in the phase positions, to determine the time deviation and / or drift, in particular the change in the difference between two forward and return path signal pairs exchanged at different times and in particular at at least approximately identical frequencies is used as a measure of the frequency deviation.

14. Method according to one of claims 1 to 13, wherein the method is carried out during and / or with an approximately unchanged radio channel or with an approximately known radio channel, distance and / or approximately known signal path length.

15. The method according to one of claims 1 to 14, wherein the relative difference, measured at two different times on received unidirectional signals, i.e. first and second time, i.e. normalized to the difference between the first and second times, of the phase shifts caused by the transmissions between the two unidirectional signals at the first and second time is used as a measure of the deviation of the PLLs of the two objects, in particular as the deviation of the local PLLs of the objects.

16. The method according to any one of claims 1 to 15, wherein the phase position of the unidirectional signal of the first object received at the second object is determined at the second object, and the phase position of the first signal at the second object relative to the PLL of the second object, in particular the difference to a phase position mathematically expected at the same frequencies of the PLLs of the two objects, is used for time synchronization.

17. Method according to one of the preceding claims, wherein the distance determination is a phase-based distance measurement 18. Method according to one of the preceding claims 1 to 16, wherein the distance determination is a travel time-based distance measurement.

19. Method according to one of the preceding claims, wherein upon acceptance of a relay attack and / or as a release decision, access or release is denied, a requested action or action is not carried out and / or an alarm or blocking is carried out and / or wherein upon non-acceptance of a relay attack and / or as a release decision, access or release is granted and / or the requested action or action is carried out and / or the alarm or blocking is not carried out.

20. Storage according to one of the preceding claims, wherein the decision is and / or includes a weighting decision and decides which measurements are used with which weight.

21. Method according to one of the preceding claims, wherein the frequency spacing between two consecutive ones of the plurality of frequencies is at least 0.1 MHz and / or a maximum of 10 MHz and / or the plurality of frequencies represent at least five frequencies and / or a maximum of 200 frequencies and / or wherein the plurality of frequencies span a frequency band of at least two MHz and / or a maximum of 100 MHz.

22. Method according to one of the preceding claims, wherein the accuracy of the distance determination is in the range from 0.3 m to 3 m, in particular at least for distances in the range from 0 to 50 m.

23. Method according to one of the preceding claims, wherein the distance determination is based on determining the signal propagation time from the first to the second or from the second to the first object and / or wherein the distance determination is based on determining the phase shift of the signals from the first to the second or from the second to the first object.

24. Method according to one of the preceding claims, wherein, in particular when determining the distance, signals received at the second or first object Signals with a received power below a predetermined and / or, in particular, lower power limit determined from or taking into account the received signals are disregarded, in particular those signals are disregarded which are more than 50% below the average power of the received signals and / or wherein, when determining the distance at the second or first object, received signals with a power above a predetermined and / or, in particular, upper power limit determined from or taking into account the received signals are disregarded.

25. Method for time synchronization, frequency synchronization and / or determining a time difference and / or frequency deviation between a first and a second object, wherein the objects each have at least one local clock and at least one PLL, wherein the time synchronization, frequency synchronization and / or determination between the objects is carried out radio-based by means of phase measurements on a plurality of signals, in particular radio signals, of different frequencies transmitted between the two objects, in particular in a round trip, characterized in that at least one difference in the phase shifts is formed by the transmission from the first to the second object and the transmission from the second to the first object and the time synchronization, frequency synchronization and / or determination is carried out based on the at least one difference.

26. Method according to the preceding claim 25, wherein the two objects emit radio signals on several frequencies and the radio signals are received by the non-transmitting of the two objects and the receiving object carries out at least one measurement of the phase relative to its clock for each frequency and / or radio signal and in particular responds thereto by emitting at least one radio signal, in particular on the same frequency, wherein the non-responding object of the two objects receives the at least one radio signal emitted as a response and carries out at least one measurement of the phase relative to its clock for each frequency and / or radio signal performs at least one measurement of the phase and / or at least one measurement of the signal arrival time and / or signal propagation time relative to its timer.

27. Method according to one of the preceding claims 25 to 36, wherein at least one second straight line difference is determined between each two of the at least one difference between the phase shifts of a signal round trip between the two objects caused by the transmission from the first to the second object and the phase shifts of a signal round trip between the two objects caused by the transmission from the first to the second object, in particular by means of negated in-line phase return, wherein the transmissions of a signal round trip from the first to the second and from the second to the first object are carried out in particular with approximately the same, in particular the same, frequency and the transmissions of different signal round trips are carried out with different frequencies between the signal round trips and wherein the distance determination, the time synchronization, frequency synchronization and / or determination is based on this at least one second straight line difference.

28. Method according to one of the preceding claims 25 to 27, wherein the time synchronization and / or determination of the time difference is carried out by determining the phase shift of the transmission of the outgoing signal from the first to the second object and the return signal from the second to the first object by means of in-line phase return.

29. The method according to claim 28, wherein the in-line phase return is realized in that the phase position of the return path signal is changed at the second object relative to a phase position known relative to the local clock of the second object, in particular the phase position of its PLL, by the negated measured phase of the forward path signal received at the second object.

30. Method according to claim 28, wherein multiple forward and return path signals are exchanged with in-line phase return, in particular at different frequencies.

31. Method according to one of claims 25 to 30, wherein a time synchronization and / or determination of the time difference takes place and wherein the phase position of the second signal received at the first object is determined at the first object and together with the phase position of the first signal at the first object with respect to the PLL of the first object, in particular the difference in the phase positions, is used for time synchronization, in particular the change in the difference between two forward and return path signal pairs exchanged at different frequencies is used as a measure of the relative change of the local clocks, in particular as their relative change.

32. Method according to one of claims 25 to 27, wherein the time synchronization and / or determination of the time difference, in particular when the distance between the objects is known, is carried out radio-based by means of a repeated, in particular exclusively, unidirectional signal exchange from the first to the second object, in particular on several frequencies, and on the basis of phase measurement(s) on the signal(s) received at the second object, in particular wherein the phase position of the unidirectional signal of the first object received at the second object is determined at the second object and the phase position of the first signal at the second object relative to the PLL of the second object, in particular the difference to a phase position mathematically expected for the same clocks, is used for time synchronization.

33. Method according to one of claims 25 to 32, wherein the method is carried out during and / or with an approximately unchanged radio channel or with an approximately known radio channel, distance and / or approximately known signal path length.

34. Method according to claim 32 or 33, wherein the relative difference of the second straight line, measured on received unidirectional signals at a first and a second frequency, i.e. normalized to the difference between the first and second frequency, of the phase shifts caused by the transmissions between the two unidirectional signals at the first and second frequency is used for time synchronization, in particular as a measure of the deviation of the local clocks, in particular multiplied by the proportionality factor two Pi as the deviation of the local clocks.

35. Method according to one of claims 25 to 34, wherein the time synchronization, frequency synchronization and / or determination of the frequency and / or time deviation is carried out by determining the phase shift of the transmission of the outgoing signal from the first to the second object and the return path signal from the second to the first object by means of in-line phase return, wherein in particular the in-line phase return is realized in that the phase position of the return path signal is changed at the second object by the negated measured phase of the outgoing signal received at the second object compared to a phase position known to the local clock of the second object, in particular the phase position of its PLL.

36. The method of claim 35, wherein multiple forward and return path signals are exchanged with in-line phase return.

37. Method according to one of claims 25 to 36, wherein the phase position of the second signal received at the first object is determined at the first object and is used together with the phase position of the first signal at the first object relative to the PLL of the first object, in particular the difference of the phase positions, for frequency synchronization and / or determination, in particular the change in the difference between two at different times and in particular, at least approximately identical frequencies, exchanged forward and return path signal pairs are used as a measure of the frequency deviation.

38. Method according to one of claims 25 to 37, wherein the frequency synchronization and / or determination of the frequency deviation, in particular with knowledge of the relative movement, in particular standstill, between the objects, is carried out radio-based by means of unidirectional signal exchange from the first to the second object, in particular at several times, and on the basis of phase measurement(s) on the signal(s) received at the second object.

39. Method according to one of claims 25 to 38, wherein the method is carried out during and / or with an approximately unchanged radio channel or with an approximately known radio channel, distance and / or approximately known signal path length.

40. Method according to one of claims 25 to 39, wherein the relative difference, measured at two different times on received unidirectional signals, i.e. first and second time, i.e. normalized to the difference between the first and second times, of the phase shifts caused by the transmissions between the two unidirectional signals at the first and second time is used as a measure of the deviation of the PLLs of the two objects, in particular as the deviation of the local PLLs of the objects.

41. Method according to one of claims 25 to 40, wherein the phase position of the unidirectional signal of the first object received at the second object is determined at the second object and the phase position of the first signal at the second object relative to the PLL of the second object, in particular the difference to a phase position mathematically expected at the same frequencies of the PLLs of the two objects, is used for time synchronization.

42. Method according to one of the preceding claims 25 to 41, wherein at least one second straight line difference is determined between the differences between two phase shifts caused by a respective signal roundabout, in particular different signal roundabouts, between the two objects, in particular with negated in-line phase return, wherein the, in particular different, signal roundabouts are carried out with signals between the signal roundabouts of different frequency and wherein the distance determination, the time synchronization, frequency synchronization and / or determination is based on this at least one second straight line difference.

43. Method according to one of the preceding claims 25 to 41, wherein the at least one difference is determined between two phase shifts caused by a transmission between the two objects, wherein the transmissions are carried out with signals of different frequencies and wherein the distance determination, the time synchronization, frequency synchronization and / or determination is based on this at least one difference.

44. Object having a timer, wherein the object is configured to emit radio signals on a plurality of frequencies and to receive radio signals from other objects and to carry out at least one measurement of the phase and / or at least one measurement of the signal arrival time and / or the signal propagation time relative to its timer on the received radio signals for each frequency and / or radio signal and in particular to respond thereto by emitting at least one radio signal, in particular on the same frequency, configured to carry out a method according to one of the preceding claims together with another, in particular identical, object.

45. A system comprising at least two objects according to the preceding claim, wherein the system is configured to carry out a method according to one of claims 1 to 43.

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